1. Field of Invention
The present invention relates to a positioning apparatus for a printer. More particularly, the present invention relates to an apparatus and a method for locating the home position or the reference position in a printer.
2. Description of Related Art
With the rapid development in the electronic industry, printing apparatuses such as copiers and printers have been widely used in daily life. The copiers and laser printers are already popular in various kinds of places, including companies, offices and families. The operations of copiers and laser printers rely on electrophotographic printing techniques. Advanced electrophotographic printing techniques enable manufacturers to provide the SOHO and families with high-quality laser printing image.
The use of color computer multimedia further increases the need of color copiers and printers. Laser printers employ complicated electrophotographic printing configuration and process to form images on an output medium. The standard electrophotographic printing processes include seven steps: charging, exposing, developing, transferring, fusing, cleaning, and erasing. The standard color printing of color printers further involves four different colored toners: yellow, magenta, cyan, and black.
In order to improve the quality of printing, quadrature incremental encoders are applied to the printers for providing the real-time displacement and speed of the organic photoconductor (OPC) belt and controlling the light source to expose predetermined positions on OPC belt at a proper moment. Furthermore, how to precisely locate the home position on the OPC belt after each pass is very important for a multi-pass printer to achieve perfect color registration. Traditionally, the home position can not be located precisely by the encoders. Thus, a home sensor with high precision is needed but it would substantially increase the manufacturing cost of the printers.
For the forgoing reasons, how to precisely locate the home position on the OPC belt without the extra expensive home sensor is what both manufacturers and users are longing for.